1. Field of the Invention
The present invention relates to an antenna module, particularly to an antenna module which facilitates heat dissipation in the IC chip to suppress the termination of communications in the case in which communications are stopped depending on the temperature of an IC (Integrated Circuit) chip.
2. Description of the Related Art
In recent years, IC media are widely available including noncontact IC cards and RFID tags in the size other than the standardized card size using RFID (radio frequency identification) technique and contact IC cards. Particularly, because of the convenience of the noncontact IC cards and the RFID tags in which the card is just placed on a card reader or held thereto to exchange information, they are applied in various fields including transportation such as the ticket gates of railroads, primarily used in this field, security systems such as access management, and product management systems in factories.
A noncontact IC card is fabricated in which an antenna coil is formed on an insulating substrate, an IC chip is mounted on the substrate to configure an antenna module, and then the antenna module is sandwiched between a pair of card forming sheets of a synthetic resin. Therefore, the noncontact IC card has semiconductor properties such as a degradation in properties and a reduction in reliability due to a temperature rise.
In recent years, as part of countermeasures to protect security against a temperature rise, it is considered to prevent a temperature rise in the IC chip caused by communications.
For this method, such a method is invented in which in a noncontact IC card having an IC chip connected to an antenna coil by wire bonding packaging, a metal foil heat sink is formed between the IC chip and an insulating substrate mounting the chip thereon, whereby the heat dissipation properties of the IC chip are improved (for example, see Patent Reference 1 (JP-A-2000-163543)).
However, in the case in which an IC chip is connected to an antenna coil by flip chip packaging, the IC chip is directly connected to an insulating substrate with bumps. Thus, it is difficult to form a metal foil heat sink between the IC chip and the insulating substrate mounting the chip thereon. Therefore, in this case, it is hard to accelerate heat dissipation in the IC chip.
In addition, as part of countermeasures to protect security against a temperature rise, such a technique is also invented in which a temperature sensor is mounted in an IC chip of a noncontact IC card and communications through an antenna coil are terminated in the case in which the temperature sensor detects that the temperature of the IC chip reaches a predetermined temperature.